1. Field of Invention
This invention relates to methods and apparatus for detecting size, location and/or orientation of a document on a platen of a copier or a scanner. More particularly, this invention relates to methods and apparatus for detecting size, location, shape and/or orientation of a document using a two-dimensional array of light sources provided on a platen cover assembly.
2. Description of Related Art
In a digital copier or a document scanner, it is desirable to accurately locate the edges of a document that has been placed on the platen of the copier or scanner. Using the detected edge information, image processing is performed to automatically deskew a copy of the document, properly register the copy on the copy paper, resize the copy to fit the selected paper size, and/or the like. One technique for locating the document edges is to use either a black or a specularly reflective platen cover. A prescan is performed with the copier's or scanner's existing document illuminator and sensor. During this prescan, the area surrounding the document appears darker than the body of the document, thereby permitting identification of the document's edges.